The invention relates to liquid handling devices. More particularly, the invention relates to devices and methods for simultaneously transferring liquid to or from multiple vessels.
A number of laboratory applications require that identical aliquots of liquid be transferred to or from multiple vessels. For example, some immunoassays employ a wash step in which identical aliquots of wash liquid are dispensed into an array of test tubes. This dispensing step may then be followed by an aspiration step in which the wash liquid is removed from each test tube. If the array of test tubes is large, this wash protocol becomes tedious if it is performed serially, i.e. one test tube at a time. As a consequence, multi-channel liquid handling devices have been developed which substantially shorten the time required to perform such protocols.
A multi-channel liquid handling device is a device which can simultaneously dispense and/or simultaneously aspirate liquid with respect to an array of vessels, i.e. two or more vessels having a fixed geometric relationship with respect to one another. The multi-channel liquid handling device includes an array of liquid conductors for simultaneously conducting liquid to or from each vessel within the array of vessels. The geometry of the array of liquid conductors corresponds to the geometry of the array of vessels so that each liquid conductor can interact with a corresponding vessel in conjunction with similar simultaneous interactions by the remaining liquid conductors and vessels.
Each liquid conductor within a multi-channel liquid handling device is connected to a source of liquid and/or vacuum. A liquid source is employed for dispensing liquid; a vacuum source is employed for aspirating liquid. A multi-channel liquid handling device may be constructed with multiple sources or with a single source. If the multi-channel liquid handling device employs multiple sources, each individual liquid conductor may be coupled to its own source. On the other hand, if the multi-channel liquid handling device employs a single source, a manifold may be employed to mediate the coupling between the array of liquid conductors and the source.
A manifold type multi-channel device is disclosed by Namba et al. (U.S. Pat. No. 4,635,665). Namba's device includes both a dispensing function and an aspiration function for transferring liquid to and from an array of wells. The dispensing function employs a manifold connected to a liquid source. The aspiration function employs a manifold connected to a vacuum source. Attached to each manifold is an array of pipettes for conducting liquid to or from the manifold. The pipettes descend from their respective manifolds. Charging the dispensing manifold with liquid allows liquid to be expressed from the array of descending pipettes. Charging the aspiration manifold with a vacuum and submerging the tips of the pipettes into liquid allows liquid to be aspirated from the array of microtiter plate wells.
It disclosed herein that, under certain circumstances, when manifold type multi-channel devices are deactivated, they may be subject to a type of leakage which is caused by siphoning. What was needed was an anti-siphon feature to prevent leakage from manifold type multi-channel dispensing and/or aspiration devices.